chasing misfire
Thread Starter
Drifting
Joined: Jan 2005
Posts: 1,354
Likes: 325
From: San Antonio Tx
chasing misfire
I've been fighting a rough idle and low speed light load misfire for a long time. Highway and full throttle is fine. Just installed new plugs, MSD wires, new ignition module and pickup coil. Did a ve learn for about 30 minites at idle and light load up to 2000 rpm's. Still rough. I checked the valve adjustment and ran a compression check, all 175 to 180# (same as when motor was new). Fuel pressure is good, ohmed the injectors, all 12.5 - 12.7. Pulled the plugs, 1, 3, 5 look good. 7 not so good. 2,4 and 8 look good 6 looks rich. Injectors are ls1's I got from SLP about 12 years ago.
And yes I checked the plug wires and they are on correctly(they are numbered and have billet wire dividers and are very easy to follow from the dist. to plugs) Anything else I should check before spending the big bucks on injectors?
And yes I checked the plug wires and they are on correctly(they are numbered and have billet wire dividers and are very easy to follow from the dist. to plugs) Anything else I should check before spending the big bucks on injectors?
Instructor
Joined: Jul 2016
Posts: 222
Likes: 11
From: Plymouth MI
I've been fighting a rough idle and low speed light load misfire for a long time. Highway and full throttle is fine. Just installed new plugs, MSD wires, new ignition module and pickup coil. Did a ve learn for about 30 minites at idle and light load up to 2000 rpm's. Still rough. I checked the valve adjustment and ran a compression check, all 175 to 180# (same as when motor was new). Fuel pressure is good, ohmed the injectors, all 12.5 - 12.7. Pulled the plugs, 1, 3, 5 look good. 7 not so good. 2,4 and 8 look good 6 looks rich. Injectors are ls1's I got from SLP about 12 years ago.
And yes I checked the plug wires and they are on correctly(they are numbered and have billet wire dividers and are very easy to follow from the dist. to plugs) Anything else I should check before spending the big bucks on injectors?
And yes I checked the plug wires and they are on correctly(they are numbered and have billet wire dividers and are very easy to follow from the dist. to plugs) Anything else I should check before spending the big bucks on injectors?
You could also check the OHM's in the two fouled plugs to ensure they are the same resistance as the other. Oh and be sure to check for vacuum leaks and the sort with a quality vacuum gauge.
Last edited by SELLC; Aug 7, 2016 at 02:01 PM.
